The farm marketing quota for any crop of wheat shall be the actual production of the acreage planted to such crop of wheat on the farm less the farm marketing excess. The farm marketing excess shall be an amount equal to twice the projected farm yield multiplied by the number of acres of such crop of wheat on the farm in excess of the farm acreage allotment for such crop unless the producer, in accordance with regulations issued by the Secretary and within the time prescribed therein, establishes to the satisfaction of the Secretary the actual production of such crop of wheat on the farm. If such actual production is so established, the farm marketing excess shall be an amount equal to the actual production of the number of acres of wheat on the farm in excess of the farm acreage allotment for such crop. In determining the farm marketing quota and farm marketing excess, any acreage of wheat remaining after the date prescribed by the Secretary for the disposal of excess acres of wheat shall be included as acreage of wheat on the farm, and the production thereof shall be appraised in such manner as the Secretary determines will provide a reasonably accurate estimate of such production. Any acreage of wheat disposed of in accordance with regulations issued by the Secretary prior to such date as may be prescribed by the Secretary shall be excluded in determining the farm marketing quota and farm marketing excess. Self-seeded (volunteer) wheat shall be included in determining the acreage of wheat. Marketing quotas for any marketing year shall be in effect with respect to wheat harvested in the calendar year in which such marketing year begins notwithstanding that the wheat is marketed prior to the beginning of such marketing year.